1. Field of the Invention
The present invention relates to a high frequency switch and a high frequency radio communication apparatus that are used for a mobile phone and the like, and, more particularly, to a high frequency switch and a high frequency radio communication apparatus that are used in four different systems.
2. Description of the Related Art
In recent years, in view of the increasing number of users of mobile communication and globalization of the systems, for example, mobile phones for four bands have been studied. Such mobile phones use four different systems of AMPS (Advanced Mobile Phone Service), EGSM (Enhanced-Global System for Mobile Communications), DCS (Digital Cellular System), and PCS (Personal Communications Services) in a single mobile phone. These systems have corresponding frequency bands of FIG. 9. Thus, high frequency switches used for such mobile phones have received attention. FIG. 9 is an explanatory drawing showing the corresponding frequencies of EGSM, AMPS, DCS, and PCS.
Here, referring to FIG. 8, which is a block diagram showing a conventional high frequency switch, the following will discuss the configuration and operation of the conventional high frequency switch used for mobile phones and so on. The conventional high frequency switch is provided for dual bands (the above-mentioned EGSM and DCS) that comprises transmission reception changeover circuits 71 and 72 and a branching filter circuit 73 of connecting the transmission reception changeover circuits 71 and 72 to an antenna (ANT). The transmission reception changeover circuit 71 has a transmitting terminal Tx1 for EGSM transmission and a receiving terminal Rx1 for EGSM reception, and the transmission reception changeover circuit 72 has a transmitting terminal Tx2 for DCS transmission and a receiving terminal Rx2 for DCS reception.
Besides, the above explanation discussed the frequency switch for dual bands as an example. High frequency switches for triple bands are also available (see U.S. Pat. No. 6,442,376).
In the future, it is expected that complexity will further increase due to multi-band configurations for four bands and so on (e.g., EGSM/AMPS/DCS/PCS). In this case, problems such as a larger circuit size arise.